Various rails have been proposed as side rails of beds. Among them, a conventional technique of foldable side rails that have plural stanchion members pivotally rotatably connected between an upper horizontal rail member and a lower horizontal rail member, to form a parallel link mechanism, wherein a holding mechanism is provided for keeping the stanchion members erect is described, for example, in Japanese Patent No. 3029026.
In the foldable side rails described in the patent document, the holding mechanism is provided at an end of the upper horizontal rail member and comprises a mechanism support member connected with the stanchion member provided at the end; the mechanism support member has a stopper pin set biased in the advancing direction by a spring; the stanchion member has a fitting hole capable of having the stopper pin set fitted in it when the stanchion member is kept erect; a release action site for allowing the stopper pin set to recede against the force of the spring is provided directly at the rear of the stopper pin set; and the bottom side of the release action site is exposed downward from the bottom of the mechanism support member. Further, the mechanism support member has a lock member capable of being moved between the release preventing position and the release allowing position for the release action site.
In the above constitution, when the stanchion members are kept erect, with the tip of the stopper pin set fitted in the fitting hole, the side rails have the upper horizontal rail member kept at the highest position in the state of use. In this constitution, a slope face for allowing the stopper pin set to slide on it is formed near the fitting hole, so that when the horizontal rail members are raised to keep the stanchion members erect, the stopper pin set can be automatically fitted into the fitting hole.
In the case where the lock member is set at the release preventing position with the stopper pin set fitted in the fitting hole, even if the release action site exposed downward from the bottom of the mechanism support member is accidentally touched to apply a force in the release allowing direction, the release action site is prevented from moving by the lock member and cannot move. Therefore, the tip of the stopper pin set remains fitted in the fitting hole, and the stanchion members and the horizontal rail members are kept in the state of use safely.
The conventional foldable side rails as described above have the following disadvantages.
1. The release action site provided of the stopper pin set is exposed downward from the bottom of the mechanism support member. So, if a force in the release allowing direction is applied owing to an accidental touch in the case where the lock member is not set at the release preventing position, it can dangerously happen that the stopper pin set is disengaged from the fitting hole and that the stanchion members fall while the upper horizontal rail member drops.
2. In the stowed state where the stanchion members fall while the upper horizontal rail member is kept at the lowest position, if the lock member is moved to the release preventing position and the horizontal rail members are raised to keep the stanchion members erect, then the stopper pin set is kept projected to interfere with the stanchion member having the fitting hole. Therefore, the stopper pin set cannot be automatically fitted into the fitting hole.
The object of this invention is to solve the above problems.